(Android) The most exciting event in May -- Google I/O

An overview of new Android's UI



Google’s Street View for Android



PacMan for Android



Google Map for Android

(Java) How to detect the end of a child thread

In a main thread, we could create the child thread to do some work in the same time. But how can we get the return value of a child thread before continue the main thread, we should wait the child thread finish before call the other method.

The solution is join() of Thread, it waits for this thread to die.

ChildThread ct = new ChildThread();
ct.start();
ct.join();

(Android) Hrizontal scroll bar doesn't work

In the android-sdk_m5-rc15_windows, the horizontal scroll bar doesn't work. There is a method setHorizontalScrollBarEnabled( Boolean ) in View class, but there is only vertical scroll bar displayed. It might be a bug in this version.

(Android) How to call another Activity from a current activiry

String cmd_execute = "am start -n package name/package name.activity name";
try {
Process child = Runtime.getRuntime().exec(cmd_execute);
Log.i("info", "execute command");
} catch (IOException e) {
e.printStackTrace();
}

(Android) How to change the screen orientation throw code

android.view.IWindowManager windowService = android.view.IWindowManager.Stub.asInterface(
android.os.ServiceManager.getService("window"));

try
{
  if (windowService.getOrientation() == 0)    //Orientation vertical
  {
      windowService.setOrientation(1);  //Orientation horizontal
      Log.i("info", "orientation 1 "+windowService.getOrientation());
  }
  else
  {
      Log.i("info", "orientation 0 "+windowService.getOrientation());
  }                    
}
catch (DeadObjectException e)
{
 e.printStackTrace();
}

(Android) How to use the CameraDevice class

After several researches of CameraDevice class, i found a good exemple to show how it works. I added a start button to launch the camera, press the middle button to save an image, the image is saved in /data/data/name of package/files/. Press the back button to continue take pictures.

package cameratest;

import java.io.FileOutputStream;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.PixelFormat;
import android.graphics.Bitmap.CompressFormat;
import android.hardware.CameraDevice;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;

public class CameraTest extends Activity{
private Preview mPreview;
private int i = 0;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle icicle) {
   super.onCreate(icicle);

   // Make sure to create a TRANSLUCENT window. This is recquired
   // for SurfaceView to work. Eventually this'll be done by
   // the system automatically.
   getWindow().setFormat(PixelFormat.TRANSLUCENT);
   mPreview = new Preview(this);

   LinearLayout layout = new LinearLayout(this);
   layout.setOrientation(LinearLayout.VERTICAL);

   Button bt = new Button(this);
   bt.setText("start");
   bt.setOnClickListener(new OnClickListener(){
       @Override
     public void onClick(View arg0) {          
         setContentView(mPreview);
     }      
   });

 layout.addView(bt, new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT,
 LayoutParams.WRAP_CONTENT));
 setContentView(layout);  
}

@Override
protected boolean isFullscreenOpaque() {
// Our main window is set to translucent, but we know that we will
// fill it with opaque data. Tell the system that so it can perform
// some important optimizations.
return true;
}

@Override
   protected void onResume()
{
   // Because the CameraDevice object is not a shared resource,
   // it's very important to release it when the activity is paused.
   super.onResume();
   mPreview.resume();
}

@Override
   protected void onPause()
{
   // Start Preview again when we resume.
   super.onPause();
   mPreview.pause();
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
   if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER)
   {
       mPreview.pause();
       takePicture();
       Log.i("info", "center key pressed cameratest");
       return true;
   }
   else if (keyCode == KeyEvent.KEYCODE_BACK)
   {
       mPreview.resume();
       Log.i("info", "back key pressed cameratest");
       return true;
   }
   return false;
}

public void takePicture(){
   CameraDevice camera = CameraDevice.open();
   if (camera != null) {
        Log.i("MyLog", "inside the camera");
        CameraDevice.CaptureParams param = new CameraDevice.CaptureParams();
        param.type = 1; // preview
        param.srcWidth = 1280;
        param.srcHeight = 960;
        param.leftPixel = 0;
        param.topPixel = 0;
        param.outputWidth = 320;
        param.outputHeight = 240;
        param.dataFormat = 2; // RGB_565
        camera.setCaptureParams(param);
  
        Bitmap myPic = Bitmap.createBitmap(320, 240, false);
        Canvas canvas = new Canvas(myPic);
        try {
             FileOutputStream stream = this.openFileOutput("picture" + i++ + ".png", 1);
             camera.capture(canvas);
             myPic.compress(CompressFormat.PNG, 100, stream);
             stream.flush();
             stream.close();
             Log.i("info", "create a picture");
        }catch(Exception e) { Log.i("info", "exception "+e.toString()); }
  
        // Make sure to release the CameraDevice
        if (camera != null)
             camera.close();
   }
}
}

class Preview extends SurfaceView implements SurfaceHolder.Callback {
SurfaceHolder  mHolder;
private PreviewThread mPreviewThread;
private boolean mHasSurface;

Preview(Context context) {
   super(context);

   // Install a SurfaceHolder.Callback so we get notified when the
   // underlying surface is created and destroyed.
   mHolder = getHolder();
   mHolder.addCallback(this);
   mHasSurface = false;

   // In this example, we hardcode the size of the preview. In a real
   // application this should be more dynamic. This guarantees that
   // the uderlying surface will never change size.
   mHolder.setFixedSize(320, 240);
}

public void resume() {
   // We do the actual acquisition in a separate thread. Create it now.
   if (mPreviewThread == null) {
       mPreviewThread = new PreviewThread();
       // If we already have a surface, just start the thread now too.
       if (mHasSurface == true) {
           mPreviewThread.start();
       }
   }
}

public void pause() {
   // Stop Preview.
   if (mPreviewThread != null) {
       mPreviewThread.requestExitAndWait();
       mPreviewThread = null;
 }
}

public void surfaceCreated(SurfaceHolder holder) {
   // The Surface has been created, start our main acquisition thread.
   mHasSurface = true;
   if (mPreviewThread != null) {
       mPreviewThread.start();
 }
}

public void surfaceDestroyed(SurfaceHolder holder) {
   // Surface will be destroyed when we return. Stop the preview.
   mHasSurface = false;
   pause();
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
   // Surface size or format has changed. This should not happen in this
   // example.
}


class PreviewThread extends Thread {
   private boolean mDone;

   PreviewThread() {
       super();
       mDone = false;
   }

   @Override
   public void run() {
       // We first open the CameraDevice and configure it.
       CameraDevice camera = CameraDevice.open();
       if (camera != null) {
           CameraDevice.CaptureParams param = new CameraDevice.CaptureParams();
               param.type = 1; // preview
               param.srcWidth      = 1280;
               param.srcHeight     = 960;
               param.leftPixel     = 0;
               param.topPixel      = 0;
               param.outputWidth   = 320;
               param.outputHeight  = 240;
               param.dataFormat    = 2; // RGB_565
           camera.setCaptureParams(param);
       }

       // This is our main acquisition thread's loop, we go until
       // asked to quit.
       SurfaceHolder holder = mHolder;
       while (!mDone) {
           // Lock the surface, this returns a Canvas that can
           // be used to render into.
           Canvas canvas = holder.lockCanvas();

           // Capture directly into the Surface
           if (camera != null) {
               camera.capture(canvas);
           }
     
           // And finally unlock and post the surface.
           holder.unlockCanvasAndPost(canvas);
       }

       // Make sure to release the CameraDevice
       if (camera != null)
           camera.close();
   }

   public void requestExitAndWait() {
       // don't call this from PreviewThread thread or it a guaranteed
       // deadlock!
       mDone = true;
       try {
 join();
     } catch (InterruptedException ex) { }
}
}
}

(Android) How to get the using memory size of Android Emulator

First you should enter to your emulator directory (for exemple: android-sdk_m5-rc15_windows/tools ) by "cmd", enter "adb shell mem_profiler" to display memory using information.